Magnetic correlations in the semimetallic hyperkagome iridate Na3Ir3O8

We present a microscopic study of a doped quantum spin liquid candidate, the hyperkagome ${\mathrm{Na}}_{3}{\mathrm{Ir}}_{3}{\mathrm{O}}_{8}$ compound, by using $^{23}\mathrm{Na}$ NMR. We determine the intrinsic behavior of the uniform q = 0 susceptibility via shift measurements and the dynamical response by probing the spin-lattice relaxation rate. Throughout the studied temperature range, the susceptibility is consistent with a semimetal behavior, though with electronic bands substantially modified by correlations. Remarkably, the antiferromagnetic fluctuations present in the insulating parent compound ${\mathrm{Na}}_{4}{\mathrm{Ir}}_{3}{\mathrm{O}}_{8}$ survive in the studied compound. The spin dynamics are consistent with ${120}^{\ensuremath{\circ}}$ excitation modes displaying short-range correlations.